Effect of pulsed bias power on electron density modulation in inductively coupled plasma

Abstract

In this study, we investigate the temporal behavior of electron density in an inductively coupled plasma (ICP) subjected to pulsed radio frequency (RF) bias using a Fourier cutoff probe measurement. This diagnostic technique enables high temporal resolution measurements at a relevant timescale, which are essential for capturing the dynamic plasma response during bias modulation. Upon the initiation of bias pulse, a transient drop in electron density—referred to as electron suction—is observed, resulting from the rapid rise in bias voltage outpacing the measured plasma response. Notably, this behavior appears in both E-mode and H-mode conditions of inductively coupled plasma (ICP) discharges, indicating that it is independent of the specific discharge mode. Furthermore, a significant electron suction is observed as the time-averaged electron density decreases. This electron suction induced by the RF pulse can be interpreted through its correlation with plasma and sheath formation. These findings provide critical insight into the transient characteristics of pulsed plasmas and offer guidance for the development of next-generation plasma-based manufacturing technologies.